1. Field of the Invention
The present invention relates to a power supply apparatus used with a display system and a method of designing the same, and more particularly, to a high-efficiency power supply apparatus used with a driving system of a display panel and a method of designing the same to improve a power efficiency by supplying a non-isolated direct current (DC) power from an input alternating current (AC) power directly to a display driving circuit. 2. Description of the Related Art
Generally, display panels, such as plasma display panels (PDPs) or ferro electric liquid crystal (FLC) panels, are driven in a digital way.
An alternating current plasma display panel (AC PDP) is a next-generation flat panel display for displaying texts or images using plasma formed by a discharging gas. Tens to hundreds of millions of pixels are arranged in a matrix form according to a size of the AC PDP.
The AC PDP has the following advantages: wide view angle, large size, long lifespan, high contrast ratio, and super-thin shape. Common disadvantages of the AC PDP are high cost and high power consumption.
FIG. 1 shows a conventional power supply apparatus used for an AC PDP.
Referring to FIG. 1, the power supply apparatus includes an AC power source 110, a rectifier circuit 120, a power factor correction circuit 130, first and second DC-DC conversion circuits 104-1 and 140-2, and a display panel driving circuit 150.
An output voltage of the second DC-DC converting circuit 140-2 is supplied to a signal and data processing circuit, such as a video signal processing circuit, and a microprocessor.
The circuit of the power supply apparatus in the conventional AC PDP is configured in a serially connected 2-stage configuration (hereinafter, referred to as a two-stage configuration) such that a DC output voltage of the power factor correction circuit 130 is supplied as an input voltage to the first and second DC-DC conversion circuits 140-1 and 140-2, and output voltages of the first and second DC-DC conversion circuits 140-1 and 140-2 are supplied to various loads.
The power supplied to the display panel driving circuit 150 is configured in the two-stage serial connection to improve the power factor and to regulate an output voltage. However, an independent DC-DC conversion circuit of a 2-TR forward or a half-bridge type should be used for the display panel driving circuit 150. The display panel driving circuit 150 uses 75% of an entire output power of the system.
However, when the power for the display panel driving circuit 150 is configured in the two-stage serial connection, the size of a plasma display panel (PDP) increases, and power efficiency is lowered since power conversion is performed twice. For example, if the efficiency of the power factor correction circuit 130 is 95% and the efficiency of the first DC-DC conversion circuit 140-1 is 95%, the efficiency of the display panel driving circuit 150 is lowered to 90%.